Inspection device, inspection facility and inspection device failure confirmation method

ABSTRACT

An inspection device is adapted for inspecting whether or not there is a foreign matter or dirt adhered to a surface of a workpiece or whether or not there is a scratch on the surface of the workpiece. A first polarizing plate having a polarizing axis in a first direction is attached to an open window of the cover part, and a second polarizing plate having a polarizing axis in a second direction orthogonal to the first direction is attached to the open window so as to open and close. In a state where the second polarizing plate is closed, the second polarizing plate overlaps the first polarizing plate. In a state where the second polarizing plate is open, the first polarizing plate and the second polarizing plate are present on a straight line connecting the outside light source and the fuel cell.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2017-203906 filed onOct. 20, 2017 including the specification, drawings and abstract isincorporated herein by reference in its entirety.

BACKGROUND 1. Technical Field

The disclosure relates to an inspection device that inspects a state ofa workpiece by irradiation, an inspection facility and an inspectiondevice failure confirmation method.

2. Description of Related Art

As this type of inspection device, disclosed is an inspection devicethat includes a mounting part, a light source part, a photographingpart, and an image processing part in a facility in a darkroom (seeJapanese Unexamined Patent Application Publication No. 2012-2792 (JP2012-2792 A)). On the mounting part, a workpiece that is a film ismounted, the light source part irradiates the workpiece, thephotographing part photographs the irradiated workpiece and outputsimage data, and the image processing part inspects whether or not thereis a defect in the workpiece based on the image data. Conventionally, inthe inspection device, noise generated when a workpiece is photographedby the photographing part is rejected by the image processing part so asto improve processing efficiency, and, at the same time, enhanceaccuracy in order to improve a defect detection rate.

SUMMARY

In the inspection device, an open window is provided in a side surfaceof the darkroom so that a failure of the inspection device is visuallyconfirmed through the open window. A shielding member such as a panel isattached to the open window in order to cover the open window so thatlight does not enter the inspection device from outside the inspectiondevice during a normal inspection. Meanwhile, when a defect happens inthe inspection device, the shielding member is removed in order toconfirm the failure of the inspection device through the open window. Inthis case, since the open window is open, there is a problem that lightsuch as indoor lighting can enter the inspection device from the outsideof the inspection device, and affect photographing in the photographingpart, thus causing an increase in misdetection.

The disclosure provides an inspection device that is able to block lightfrom entering the inspection device from the outside of the inspectiondevice when the inside of the inspection device is visually inspected.The disclosure also provides an inspection device failure confirmationmethod.

A first aspect of the disclosure relates to an inspection device thatinspects whether or not there is a foreign matter or dirt adhered to asurface of a workpiece or whether or not there is a scratch on thesurface of the workpiece. The inspection device includes a mounting parton which the workpiece is mounted, a light source part that irradiatesthe surface of the workpiece, and a cover part that covers the mountingpart and the light source part and blocks light from an outside lightsource from entering the inspection device, the outside light sourcebeing positioned outside the inspection device. A first polarizing platehaving a polarizing axis in a first direction is attached to an openwindow provided in the cover part, and a second polarizing plate havinga polarizing axis in a second direction orthogonal to the firstdirection is attached to the open window so that the second polarizingplate is able to open and close. The second polarizing plate overlapsthe first polarizing plate in a state where the second polarizing plateis closed, and the first polarizing plate and the second polarizingplate are present on a straight line that connects the outside lightsource and the workpiece in a state where the second polarizing plate isopen.

In the inspection device, the first polarizing plate having thepolarizing axis in the first direction is attached to the open window ofthe cover part, and the second polarizing plate having the polarizingaxis in the second direction orthogonal to the first direction isattached to the open window so that the second polarizing plate is ableto open and close. The first polarizing plate has the polarizing axis inthe first direction. Light advances while oscillating perpendicularly tothe advancing direction. In other words, light advances while making atransverse wave. Therefore, the first polarizing plate only allowstransmission of the transverse wave in the first direction along thepolarizing axis. Meanwhile, the second polarizing plate has thepolarizing axis in the second direction orthogonal to the firstdirection. The second polarizing plate only allows transmission of atransverse wave in the second direction along the polarizing axis. Inother words, the transverse wave in directions other than the seconddirection is not able to transmit through the second polarizing plate.Therefore, when the first polarizing plate and the second polarizingplate overlap each other so that the polarizing axis in the firstdirection and the polarizing axis in the second direction becomeorthogonal to one another, light is not able to transmit through theoverlapped first polarizing plate and second polarizing plate.

As a result, in the state where the second polarizing plate is closed,the second polarizing plate overlaps the first polarizing plate so thatthe polarizing axis in the first direction and the polarizing axis inthe second direction become orthogonal to one another. Therefore, lightis not able to transmit through the first polarizing plate and thesecond polarizing plate that overlap each other, and light coming fromthe outside light source positioned outside the inspection device isblocked from entering the inspection device.

Further, the inspection device is structured so that, in the state wherethe second polarizing plate is open, the first polarizing plate and thesecond polarizing plate are present on the straight line that connectsthe outside light source and the workpiece with each other. The firstpolarizing plate and the second polarizing plate are provided so thatthe polarizing axis in the first direction and the polarizing axis inthe second direction are orthogonal to each other. With the structure,only a transverse wave of light in the second direction transmitsthrough the second polarizing plate, but the transmitted transverse wavein the second direction is not able to transmit through the firstpolarizing plate that has the polarizing axis in the first directionorthogonal to the second direction. As a result, even in the state wherethe second polarizing plate is open, light from the outside light sourcepositioned outside the inspection device is blocked from entering theinspection device.

In the state where the second polarizing plate is open, an angle betweenthe second polarizing plate and the first polarizing plate may be 90degrees or smaller.

When the angle between the second polarizing plate and the firstpolarizing plate is 90 degrees or smaller in the state where the secondpolarizing plate is open, the second polarizing plate and the firstpolarizing plate block more light trying to enter the inspection devicefrom the outside light source.

The open window of the cover part may be provided in a side surface ofthe cover part and also at a position lower than the outside lightsource. The second polarizing plate may be attached so as to be able toopen upwardly with respect to the open window.

The open window of the cover part is provided in the side surface of thecover part and also at a position lower than the outside light source,and the second polarizing plate is attached to the open window so thatthe second polarizing plate is able to open upwardly. Therefore, whenthe second polarizing plate is open, the second polarizing plate and thefirst polarizing plate block more light trying to enter the inspectiondevice from the outside light source through the open window.

The inspection device may have a holding device that is configured tohold the second polarizing plate in the open state.

Since the holding device keeps the second polarizing plate open, it isnot necessary to support the second polarizing plate in the open statewith a hand when a visual inspection of the inside of the inspectiondevice is carried out through the first polarizing plate attached to theopen window. Thus, it is possible to carry out an inspection work of theinside of the inspection device easily.

The workpiece may include a fuel cell (a cell of a fuel cell stack).

An outside shape of the fuel cell serving as the workpiece is complex,and irradiation of the fuel cell by the light source part is easilyaffected by light that is incident from the outside light source. Sincethe second polarizing plate and the first polarizing plate block lighttrying to enter the inspection device from the outside light source, theinspection of the fuel cell is not affected by light entering theinspection device from the outside light source, and is thus carried outhighly accurately.

A second aspect of the disclosure relates to an inspection facility thatinspects whether or not there is a foreign matter or dirt adhered to asurface of a workpiece or whether or not there is a scratch on thesurface of the workpiece, the inspection facility including theinspection device and the outside light source.

A third aspect of the disclosure relates to an inspection device failureconfirmation method in which a failure of an inspection device isconfirmed, the inspection device detecting whether or not there is aforeign matter or dirt adhered to a surface of a workpiece or whether ornot there is a scratch on the surface of the workpiece. The inspectiondevice includes a mounting part on which the workpiece is mounted, alight source part that irradiates a surface of the workpiece, and acover part that covers the mounting part and the light source part andblocks light coming from an outside light source from entering theinspection device, the outside light source being positioned outside theinspection device. The first polarizing plate having a polarizing axisin a first direction is attached to an open window provided in the coverpart, and a second polarizing plate having a polarizing axis in a seconddirection orthogonal to the first direction is attached to the openwindow so that the second polarizing plate is able to open and close.The outside light source and the inspection device are arranged so thatthe second polarizing plate overlaps the first polarizing plate in astate where the second polarizing plate is closed, and the firstpolarizing plate and the second polarizing plate are present on astraight line that connects the outside light source and the workpiecein the state where the second polarizing plate is open. The inside ofthe inspection device is visually inspected through the first polarizingplate in the state where second polarizing plate is open so that it isable to confirm whether or not there is a failure in the inspectiondevice.

The inspection device that is confirmed by using the inspection devicefailure confirmation method is structured similarly to the inspectiondevice according to the first aspect of the disclosure. Therefore,whether the second polarizing plate is closed or open, light from theoutside light source positioned outside the inspection device is blockedfrom entering the inspection device. As a result, it is possible tocarry out a visual inspection of the inside of the inspection devicethrough the first polarizing plate having the polarizing axis in thefirst direction in the state where the second polarizing plate is openand light from the outside light source is blocked from entering theinspection device. With the visual inspection, it is possible to confirma failure of the inspection device without being affected by light fromthe outside light source.

In the state where the second polarizing plate is open, an angle betweenthe second polarizing plate and the first polarizing plate may be 90degrees or smaller

When the angle between the second polarizing plate and the firstpolarizing plate is 90 degrees or smaller in the state where the secondpolarizing plate is open, the second polarizing plate and the firstpolarizing plate block more light that tries to enter the inspectiondevice from the outside light source, and, in this state, a visualinspection of the inside of the inspection device is carried out throughthe first polarizing plate. With the visual inspection, it is possibleto confirm a failure of the inspection device without being affected bylight from the outside light source.

The workpiece may include a fuel cell.

An outside shape of the fuel cell serving as the workpiece is complex,and irradiation of the fuel cell by the light source part is easilyaffected by light that is incident from the outside light source. Sincethe second polarizing plate and the first polarizing plate block lighttrying to enter the inspection device from the outside light source,failure confirmation of the fuel cell in the inspection device is notaffected by light entering the inspection device from the outside lightsource, and is thus carried out highly accurately.

According to the disclosure, it is possible to provide the inspectiondevice that is able to block entry of light into the inspection devicefrom outside of the inspection device when a visual inspection of theinside of the inspection device is carried out. Also, the inspectiondevice failure confirmation method is provided.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance ofexemplary embodiments of the disclosure will be described below withreference to the accompanying drawings, in which like numerals denotelike elements, and wherein:

FIG. 1 is partial sectional view of a fuel cell to be inspected by aninspection device according to an embodiment of the disclosure;

FIG. 2 is a process flow showing a manufacturing process for the fuelcell to be inspected by the inspection device according to theembodiment of the disclosure;

FIG. 3 is a side view of an inspection facility including the inspectiondevice according to the embodiment of the disclosure;

FIG. 4A is a side view of the inspection device according to theembodiment of the disclosure, showing a part of the inspection device;

FIG. 4B is a side view of the inspection device according to theembodiment of the disclosure, and is an enlarged side view of a part ofthe inspection device;

FIG. 5A is a partial sectional view in which the inspection deviceaccording to the embodiment of the disclosure is cut off in a statewhere a second polarizing plate is closed;

FIG. 5B is a partial sectional view in which the inspection deviceaccording to the embodiment of the disclosure is cut off in a statewhere the second polarizing plate is open; and

FIG. 6 is a view describing transmission of light through the secondpolarizing plate and a first polarizing plate of the inspection deviceaccording to the embodiment of the disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

An inspection device 100 and an inspection device failure confirmationmethod according to an embodiment are described with reference to thedrawings. An inspection device and an inspection device failureconfirmation method according to the disclosure are applied to theembodiment.

A workpiece inspected by the inspection device 100 according to theembodiment is not particularly limited as an inspection object, but maybe made of, for example, a fuel cell 10 (a cell of a fuel cell stack).As shown in FIG. 1, the fuel cell 10 includes a membrane electrode andgas diffusion layer assembly (hereinafter referred to as an MEGA) 20, aseal member 30, and a separator 40.

The MEGA 20 includes a membrane electrode assembly (hereinafter referredto as an MEA) 21, an anode-side gas diffusion layer (hereinafterreferred to as a GDL) 22, and a cathode-side GDL 23.

The MEA 21 is made of an assembly of an electrolyte membrane (notshown), an anode catalyst layer, and a cathode catalyst layer. Theelectrolyte membrane is formed by using a polymer electrolyte resin thatis a solid polymeric material such as perfluorosulfonic acid (PFSA)ionomer, and is made of an ion exchange membrane in which anion-conductive polymer membrane serves as an electrolyte. Theelectrolyte membrane has functions of obstructing flows of electrons andgas and allowing protons to move from the anode catalyst layer to thecathode catalyst layer.

The anode catalyst layer is an electrode catalyst layer that is formedby coating a carbon particle with proton-conductive ionomer. The carbonparticle is, for example, a catalyst-carrying carbon particle that ismade of a conductive carrier carrying a catalyst such as platinum, aplatinum alloy, and so on. The anode catalyst layer has a function ofbreaking down hydrogen gas (H₂) into protons and electrons. Although thecathode catalyst layer is made from materials similar to those of theanode catalyst layer, the cathode catalyst layer has a function ofgenerating water out of protons, electrons, and oxygen, unlike the anodecatalyst layer.

The anode-side GDL 22 is made from a material having gas permeabilityand conductivity, that is, for example, a porous fiber base materialsuch as carbon paper in which carbon fiber, graphite fiber, or the likeis used. The anode-side GDL 22 is joined to an outer side of the anodecatalyst layer, and has a function of diffusing hydrogen gas serving asfuel gas so that hydrogen gas is made uniform and spreads across theanode catalyst layer.

Similarly to the anode-side GDL 22, the cathode-side GDL 23 is made froma material having gas permeability and conductivity, that is, forexample, a porous fiber base material such as carbon paper in whichcarbon fiber, graphite fiber, or the like is used. The cathode-side GDL23 is joined to an outer side of the cathode catalyst layer, and has afunction of diffusing air (O₂) serving as oxidant gas so that air ismade uniform and spreads across the cathode catalyst layer.

The seal member 30 is made from synthetic resin and formed into a frameshape. The MEGA 20 is joined to the seal member 30. The seal member 30has a function of preventing so-called cross leakage and electricalshort circuit between catalytic electrodes. Cross leakage means thatsmall amounts of hydrogen (H₂) of a fuel electrode and oxygen (O₂) of anair electrode pass through the electrolyte membrane.

The separator 40 includes an anode-side separator 41 and a cathode-sideseparator 42. The anode-side separator 41 is joined to the anode-sideGDL 22 of the MEGA 20, and a fuel gas flow passage 41 a is formed alonga surface of the anode-side GDL 22. In fuel gas flow passage 41 a,hydrogen serving as fuel gas is allowed to flow. The cathode-sideseparator 42 is joined to the cathode-side GDL 23 of the MEGA 20, and anoxidant gas flow passage 42 a is formed along a surface of thecathode-side GDL 23. In the oxidant gas flow passage 42 a, air servingas oxidant gas is allowed to flow.

Next, a manufacturing method for the fuel cell 10 including theinspection device 100 and the inspection device failure confirmationmethod according to the embodiment is described with reference to thedrawings.

As shown in FIG. 2, the manufacturing method for the fuel cell 10according to the embodiment includes an MEGA subassembly fabricationstep, a cell joining step, a cell inspection step, an appearanceinspection step, and a cell lamination step. These steps are carried outin order.

In the MEGA subassembly fabrication step, the anode-side GDL 22 and thecathode-side GDL 23 are joined to the MEA 21 transferred from a previousstep, and the MEGA 20 is thus fabricated. Next, the seal member 30 isjoined to the fabricated MEGA 20, and an adhesive sheet is assembled tothe seal member 30. Thus, an MEGA subassembly is fabricated (step S1).

In the cell joining step, the MEGA subassembly transferred from the MEGAsubassembly fabrication step and the separator 40 fabricated in adifferent step (not shown) are assembled, and the fuel cell 10 is thusfabricated (step S2). The separator 40 is made of the anode-sideseparator 41 and the cathode-side separator 42. The anode-side separator41 is joined to the anode-side GDL 22 of the MEGA subassembly, and thecathode-side separator 42 is joined to the cathode-side GDL 23 in theMEGA subassembly.

As shown in FIG. 3, in the cell inspection step, the fuel cell 10fabricated in the cell joining step is inspected in an inspectionfacility 200. The inspection facility 200 includes a feed part 210,various inspection parts 220, an appearance inspection part 230, adischarge part 240, and a transfer part 250. In the inspection facility200, the fuel cell 10 fed from the feed part 210 is transferred by thetransfer part 250 in a transfer direction shown by an arrow h, anddischarged from the discharge part 240 after going through the variousinspection parts 220 and the appearance inspection part 230.

In the cell inspection step, various inspections other than appearanceinspection that is carried out later in the appearance inspection stepare carried out for the fuel cell in the various inspection parts 220(step S3). The fuel cell 10 determined as a defect in the cellinspection step is discarded as a defect (step S6). The fuel cell 10that is not determined as a defect in the cell inspection step istransferred to the appearance inspection step.

In the appearance inspection step, the fuel cell 10 transferred by thetransfer part 250 is inspected in the appearance inspection part 230 ofthe inspection facility 200 to determine whether or not there isabnormality in an appearance of the fuel cell 10 such as adhesion of aforeign matter or dirt, and a scratch (step S4). The inspection device100 that structures the appearance inspection part 230 carries out theappearance inspection step.

As shown in FIG. 4A, FIG. 4B, FIG. 5A, and FIG. 5B, the inspectiondevice 100 includes a mounting part, the light source part 110, a coverpart 120, a pair of polarization parts 130, a detection part 140, and acontrol part (not shown). The mounting part structures the transfer part250 of the inspection facility 200, and the fuel cell 10 is mounted onthe mounting part.

The fuel cell 10 is mounted on the mounting part that serves as thetransfer part 250, and the mounting part transfers the fuel cell 10 atgiven transfer speed (m/second) in the transfer direction shown by thearrow h. The light source part 110 is made of a plurality of lightsources that are provided inside the inspection device 100 correspondingto a complex outer shape of the fuel cell 10, and irradiates the fuelcell 10 with light coming from each of the light sources.

The cover part 120 is made of a wall member that entirely covers thetransferred fuel cell 10, the mounting part, and the light source part110, and blocks light from an outside light source 300 positionedoutside the inspection device 100 so that the light does not enter theinspection device 100. Therefore, the inside of the inspection device100 covered by the cover part 120 becomes a darkroom. A pair ofrectangular open windows 120 a is provided in the wall member of thecover part 120 on one side. The open windows 120 a go through the wallmember and separated from one another in the transfer direction. Througheach of the open windows 120 a, one is able to see the inside of theinspection device 100 from the outside of the inspection device 100.

The open windows 120 a are provided on a side surface of the cover part120 at positions lower than the outside light source 300. When theinspection device 100 is installed on a floor surface of a building, alighting fixture attached to a ceiling of the building serves as theoutside light source 300, and light from the lighting fixture hits theopen windows 120 a from above.

As shown in FIG. 4A, the polarization parts 130 are attached to the openwindows 120 a of the cover part 120, respectively. As shown in FIG. 5Aand FIG. 5B, each of the polarization parts 130 is made of a firstpolarizing plate 131, a second polarizing plate 132, a pair of hinges133, and a pair of handgrips 134.

The first polarizing plate 131 is made of a transparent member, and hasa polarizing axis p1 in a first direction. Light advances whileoscillating perpendicularly to the advancing direction. In other words,light advances while making a transverse wave. Therefore, the firstpolarizing plate 131 allows transmission of the transverse wave in thefirst direction along the polarizing axis p1 only. Here, the firstdirection means a direction perpendicular to the transfer directionshown by the arrow h in FIG. 4A. As shown in FIG. 5A and FIG. 5B, thefirst polarizing plate 131 is tightly fitted into the open window 120 aand fixed.

Similarly to the first polarizing plate 131, the second polarizing plate132 is made of a transparent member, and has a polarizing axis p2 in asecond direction orthogonal to the first direction. The secondpolarizing plate 132 allows transmission of a transverse wave of lightin the second direction along the polarizing axis p2 only. The seconddirection means the transfer direction shown by the arrow h in FIG. 4A.As shown in FIG. 5A and FIG. 5B, the second polarizing plate 132 isattached to the cover part 120 in the vicinity of the open window 120 aby the hinges 133 so that the second polarizing plate 132 is able toopen and close.

The second polarizing plate 132 is attached so as to be able to openupwardly with respect to the open window 120 a. One end of the secondpolarizing plate 132 is pivotally supported by the hinges 133 in theside surface of the cover part 120 and also in the vicinity of an upperend of the open window 120 a, and the second polarizing plate 132 isopen as the other end of the second polarizing plate 132 is lifted inthe upward direction that is a direction away from the side surface ofthe cover part 120. A holding device is provided between the secondpolarizing plate 132 and the cover part 120. The holding device isstructured so as to be able to hold the second polarizing plate 132 inan open state, and the second polarizing plate 132 is thus able to standstill at an arbitrary angle θ.

In the description above, the first direction of the polarizing axis p1of the first polarizing plate 131 is referred to as a directionperpendicular to the transfer direction shown by the arrow h in FIG. 4A,and the second direction of the polarizing axis p2 of the secondpolarizing plate 132 is referred to as the transfer direction shown bythe arrow h in FIG. 4A. However, the first direction and the seconddirection may be other directions as long as they are orthogonal to eachother. For example, the polarizing axis p1 of the first polarizing plate131 may be in the second direction, and the polarizing axis p2 of thesecond polarizing plate 132 may be in the first direction.

When the second polarizing plate 132 overlap the first polarizing plate131 as shown in FIG. 4B and FIG. 5A, in other words, when the secondpolarizing plate 132 is closed, the polarizing axis p2 in the seconddirection and the polarizing axis p1 in the first direction becomeorthogonal to one another. In this case, as shown in FIG. 6, thedirection of the transverse wave of light shown by a curve c coincideswith the second direction of the polarizing axis p2 of the secondpolarizing plate 132. Therefore, the transverse wave of light shown bythe curve c transmits through the second polarizing plate 132 andreaches the first polarizing plate 131.

However, the direction of the transverse wave of light shown by thecurve c does not coincide with the first direction of the polarizingaxis p1 of the first polarizing plate 131. This means that the directionof the transverse wave of light shown by the curve c is orthogonal tothe first direction of the polarizing axis p1 of the first polarizingplate 131. Therefore, the transverse wave of light shown by the curve cis not able to transmit through the first polarizing plate 131, and isblocked by the first polarizing plate 131. As a result, in the stateshown in FIG. 5A where the second polarizing plate 132 is closed, lightfrom the outside light source 300 of the inspection device 100 isblocked by the second polarizing plate 132 and the first polarizingplate 131, and is not able to enter the inspection device 100.

The transverse wave of light shown by a straight line S in FIG. 6 doesnot coincide with the second direction of the polarizing axis p2 of thesecond polarizing plate 132. Therefore, the transverse wave of light isnot able to transmit through the second polarizing plate 132, and isblocked by the second polarizing plate 132.

The inspection device 100 is structured so that, in the state where thesecond polarizing plate 132 is open as shown in FIG. 5B, the firstpolarizing plate 131 and the second polarizing plate 132 are present ona straight line L that connects a center portion of the outside lightsource 300 of the inspection device 100 and a center portion of the fuelcell 10 serving as a workpiece. With the structure, similarly to thestate where the second polarizing plate 132 is closed, when the secondpolarizing plate 132 is open, light traveling from the outside lightsource 300 towards the inside of the inspection device 100 is able totransmit through the second polarizing plate 132, but is blocked by thefirst polarizing plate 131 and is thus not able to enter the inspectiondevice 100.

Hence, when the second polarizing plate 132 is open, it is preferredthat an angle θ between the second polarizing plate 132 and the firstpolarizing plate 131 shown in FIG. 5B, in other words, anopening-closing angle θ be an angle that makes it possible to block asmuch light from the outside light source 300 as possible. On the otherhand, when an operator visually inspects the inside of the inspectiondevice 100 from the first polarizing plate 131 in the state where thesecond polarizing plate 132 is open, it is preferred that the secondpolarizing plate 132 is open at the largest possible angle so as not toobstruct the operation. Specifically, it is preferred that the angle θis in a range from about 80 degrees to 100 degrees, and an angle of 90degrees is the most preferred.

As shown in FIG. 4A and FIG. 4B, the handgrips 134 are attached to thesecond polarizing plate 132 so as to be separated from each other alongthe transfer direction shown by the arrow h. When an operator opens orcloses the second polarizing plate 132, the operator grips the handgrips134.

The detection part 140 is made of a device that detects appearance ofthe fuel cell 10 and captures it as an image. The detection part 140includes, for example, an image pickup device such as a charge-coupleddevice (CCD) image sensor and a complementary metal-oxide-semiconductor(CMOS) image sensor. An image captured by the detection part 140 istransmitted to the control part. Based on the transmitted image, thecontrol part detects whether or not a foreign matter or dirt is adheredto the fuel cell 10, or the fuel cell 10 is scratched, and determineswhether or not the fuel cell 10 is a defect.

In the cell lamination step, a stack is formed by laminating a pluralityof the fuel cells 10, and the laminated fuel cells 10 are electricallyconnected with each other. Conductive collector plates are arranged onouter sides of both ends of the stack in a lamination direction of thefuel cells 10, respectively, and the collector plates are electricallyconnected with the stack. A pair of endplates is arranged on outer sidesof the collector plates, respectively. The endplates sandwich the stackand are insulated from the collector plates. The endplates are fastenedby side plates, respectively, and the endplates thus cover a peripheryof the stack so that the stack is held (step S5). The stack in which thefuel cells 10 are laminated is transferred to the next step.

Next, the inspection device failure confirmation method according to theembodiment is described with reference to the drawings.

The inspection device failure confirmation method according to theembodiment is made of a method of confirming whether or not theinspection device 100 has a failure. As shown in FIG. 5B, this method isstructured so that a failure of the inspection device 100 is confirmedas the inside of the inspection device 100 is visually inspected throughthe first polarizing plate 131 in the state where the second polarizingplate 132 of the polarization part 130 of the inspection device 100 isopen.

In the inspection device failure confirmation method according to theembodiment, as described earlier, light from the outside light source300 is blocked by the second polarizing plate 132 and the firstpolarizing plate 131 from entering the inspection device 100 even whenthe second polarizing plate 132 is open. Therefore, it is possible toconfirm a failure of the inspection device 100 through the transparentfirst polarizing plate 131 without being affected by light form theoutside light source 300.

Effects of the inspection device 100 and the inspection device failureconfirmation method structured as above according to the embodiment aredescribed.

In the inspection device 100 according to the embodiment, the firstpolarizing plate 131 having the polarizing axis p1 in the firstdirection is attached to each of the open windows 120 a on the sidesurface of the cover part 120. Also, the second polarizing plate 132having the polarizing axis p2 in the second direction orthogonal to thefirst direction is attached to each of the open windows 120 a. With thisstructure, the polarizing axis p1 of the first polarizing plate 131 isin the first direction, and light advances in the transverse wave thatis perpendicular to the advancing direction. Therefore, only thetransverse wave in the first direction along the polarizing axis p1transmits through the first polarizing plate 131.

Meanwhile, the polarizing axis p2 of the second polarizing plate 132 isin the second direction orthogonal to the first direction, and only thetransverse wave in the second direction along the polarizing axis p2transmits through the second polarizing plate 132. In other words, thetransverse wave in directions other than the second direction is notable to transmit through the second polarizing plate 132. Therefore,when the first polarizing plate 131 and the second polarizing plate 132overlap each other so that the polarizing axis p1 in the first directionand the polarizing axis p2 in the second direction become orthogonal toone another, light is not able to transmit through the first polarizingplate 131 and the second polarizing plate 132 that overlap each other.

With the structure, in the state where the second polarizing plate 132is closed, the second polarizing plate 132 overlaps the first polarizingplate 131 so that the polarizing axis p1 in the first direction and thepolarizing axis p2 in the second direction become orthogonal to oneanother. Therefore, light is not able to transmit through the firstpolarizing plate 131 and the second polarizing plate 132 that overlapeach other, and light from the outside light source 300 that ispositioned outside the inspection device 100 is blocked from enteringthe inspection device 100.

As a result, with the inspection device 100 according to the embodiment,an effect is obtained that light from the outside light source 300 isblocked from entering the inspection device 100 in the state where thesecond polarizing plate 132 is closed, and the darkroom inside theinspection device 100 is not affected by the outside light source 300.

Further, the inspection device 100 according to the embodiment isstructured so that the first polarizing plate 131 and the secondpolarizing plate 132 are present on the straight line L that connectsthe outside light source 300 and the fuel cell 10 in the state where thesecond polarizing plate 132 is open. Even when the second polarizingplate 132 is open, the first polarizing plate 131 and the secondpolarizing plate 132 maintain a relation that the polarizing axis p1 inthe first direction and the polarizing axis p2 in the second directionare orthogonal to each other.

With the structure, only the transverse wave, c of light in the seconddirection transmits through the second polarizing plate 132, but thetransmitted transverse wave c in the second direction is not able totransmit through the first polarizing plate 131 that has the polarizingaxis p1 in the first direction orthogonal to the second direction. As aresult, even in the state where the second polarizing plate 132 is open,light from the outside light source 300 that is positioned outside theinspection device 100 is blocked from entering the inspection device100. Hence, even in the state where the second polarizing plate 132 isopen, the darkroom inside the inspection device 100 is not affected bylight from the outside light source 300. Therefore, an effect isobtained that misdetection by the detection part 140 is prevented, andthe fuel cell 10 having a complex outside shape is inspected highlyaccurately.

Further, the inspection device 100 according to the embodiment isstructured so that, in the state where the second polarizing plate 132is open, an angle between the second polarizing plate 132 and the firstpolarizing plate 131 becomes 90 degrees or smaller, and entrance oflight from the outside light source 300 is blocked as much as possible.With the structure, the second polarizing plate 132 and the firstpolarizing plate 131 block as much light as possible that tries to enterthe inspection device 100 from the outside light source 300. As aresult, an effect is obtained that there is no influence imposed bylight coming from the outside light source 300, misdetection by thedetection part 140 is thus prevented, and the fuel cell 10 having thecomplex outside shape is inspected highly accurately.

Furthermore, in the inspection device 100 according to the embodiment,the second polarizing plate 132 is attached to the cover part 120 in amovable manner, in other words, the second polarizing plate 132 isattached to the cover part 120 through the hinges 133 so that the secondpolarizing plate 132 is able to open and close. Therefore, it ispossible to repeat the inspection in the same conditions. Thus, aneffect is obtained that while maintaining illuminance for operationscarried out outside the facility, inspection conditions are stabilizedfor both normal inspection and inspection at the time of a defect, inother words, for both steady and non-steady time. Therefore, it ispossible to maintain quality and operations.

Further, in the inspection device 100 according to the embodiment, theopen windows 120 a of the cover part 120 are provided in the sidesurface of the cover part 120 and also at positions lower than theoutside light source 300. The second polarizing plate 132 is attached soas to be able to open upwardly with respect to each of the open windows120 a. Therefore, in the state where the second polarizing plate 132 isopen upwardly, the second polarizing plate 132 and the first polarizingplate 131 block as much light as possible that tries to enter theinspection device 100 from the outside light source 300 through the openwindow 120 a.

The inspection device failure confirmation method according to theembodiment is structured so that, when a failure of the inspectiondevice 100 according to the embodiment is confirmed, an operatorvisually inspects the inside of the inspection device 100 through thefirst polarizing plate 131 in the state where the second polarizingplate 132 is open. With the structure, when the operator confirms adefect inside the inspection device 100 from the outside of theinspection device 100, light from the outside light source 300 is keptblocked from entering the inspection device 100 even in the state wherethe second polarizing plate 132 is open. In this state, the operator isable to visually inspect the inside of the inspection device 100 throughthe transparent first polarizing plate 131 having the polarizing axis p1in the first direction. Thus, an effect is obtained that, with thevisual inspection, a failure of the inspection device is confirmedwithout being affected by light from the outside light source 300.

In related arts, when a failure of the inside of an inspection device isconfirmed, a detachable panel provided in a wall surface of theinspection device is removed, and a visual inspection of the inside iscarried out through an opening portion to confirm the failure. With thismethod, light from an outside light source enters the inspection devicefrom the opening portion at the time of the visual inspection. Thiscauses a problem that misdetection increases, making it difficult tomaintain quality of fuel cells and operation of the device. On thecontrary, with the inspection device failure confirmation methodaccording to the embodiment, there is an effect that light from theoutside light source does not enter the inspection device, and theproblem of the related arts is solved.

Further, the inspection device 100 according to the embodiment isprovided with the holding device that is structured so as to hold thesecond polarizing plate 132 in the opened state. Therefore, when avisual inspection of the inside of the inspection device 100 is carriedout through the first polarizing plate 131 attached to each of the openwindows 120 a, an operator does not need to support the secondpolarizing plate 132 in the open state, and it is thus possible to carryout inspection work for the inside of the inspection device 100 easily.

Further, in the inspection device failure confirmation method accordingto the embodiment, the angle between the second polarizing plate 132 andthe first polarizing plate 131 is 90 degrees or smaller in the statewhere the second polarizing plate 132 is open, so that entrance of lightfrom the outside light source 300 is blocked as much as possible. Withthe structure, the second polarizing plate 132 and the first polarizingplate 131 block as much light as possible that tries to enter theinspection device 100 from the outside light source 300. As a result,the inside of the inspection device 100 is visually inspected throughthe first polarizing plate 131 without being affected by light from theoutside light source 300. Thus, an effect is obtained that the visualinspection makes it possible to confirm a failure of the inspectiondevice without being affected by light from the outside light source300.

The embodiment according to the disclosure has been described in detail.However, the disclosure is not limited to the embodiment, and variousdesign changes may be made.

What is claimed is:
 1. An inspection device that inspects whether or notthere is a foreign matter or dirt adhered to a surface of a workpiece orwhether or not there is a scratch on the surface of the workpiece, theinspection device comprising: a mounting part on which the workpiece ismounted; a light source part that irradiates the surface of theworkpiece; and a cover part that covers the mounting part and the lightsource part and blocks light coming from an outside light source fromentering the inspection device, the outside light source beingpositioned outside the inspection device, wherein: a first polarizingplate having a polarizing axis in a first direction is attached to anopen window provided in the cover part, and a second polarizing platehaving a polarizing axis in a second direction orthogonal to the firstdirection is attached to the open window so that the second polarizingplate is able to open and close; and the second polarizing plateoverlaps the first polarizing plate in a state where the secondpolarizing plate is closed, and the first polarizing plate and thesecond polarizing plate are present on a straight line that connects theoutside light source and the workpiece in a state where the secondpolarizing plate is open.
 2. The inspection device according to claim 1,wherein an angle between the second polarizing plate and the firstpolarizing plate is 90 degrees or smaller in the state where the secondpolarizing plate is open.
 3. The inspection device according to claim 1,wherein: the open window of the cover part is provided in a side surfaceof the cover part and at a position lower than the outside light source;and the second polarizing plate is attached so as to be able to openupwardly with respect to the open window.
 4. The inspection deviceaccording to claim 3, further comprising a holding device that isconfigured to hold the second polarizing plate in the state where thesecond polarizing plate is open.
 5. The inspection device according toclaim 1, wherein the workpiece includes a fuel cell.
 6. An inspectionfacility that detects whether or not there is a foreign matter or dirtadhered to a surface of a workpiece or whether or not there is a scratchon the surface of the workpiece, the inspection facility comprising: theinspection device according to claim 1; and the outside light source. 7.An inspection device failure confirmation method in which a failure ofan inspection device is confirmed, the inspection device detectingwhether or not there is a foreign matter or dirt adhered to a surface ofa workpiece or whether or not there is a scratch on the surface of theworkpiece, wherein: the inspection device includes a mounting part onwhich the workpiece is mounted, a light source part that irradiates thesurface of the workpiece, and a cover part that covers the mounting partand the light source part and blocks light coming from an outside lightsource from entering the inspection device, the outside light sourcebeing positioned outside the inspection device; a first polarizing platehaving a polarizing axis in a first direction is attached to an openwindow provided in the cover part, and a second polarizing plate havinga polarizing axis in a second direction orthogonal to the firstdirection is attached to the open window so as to be able to open andclose; the inspection device failure confirmation method, comprising:installing the outside light source and the inspection device so thatthe second polarizing plate overlaps the first polarizing plate in astate where the second polarizing plate is closed, and the firstpolarizing plate and the second polarizing plate are present on astraight line that connects the outside light source and the workpiecein the state where the second polarizing plate is open; and inspectingan inside of the inspection device visually through the first polarizingplate in the state where the second polarizing plate is open so that itis able to confirm whether or not there is a failure in the inspectiondevice.
 8. The inspection device failure confirmation method accordingto claim 7, wherein an angle between the second polarizing plate and thefirst polarizing plate is 90 degrees or smaller in the state where thesecond polarizing plate is open.
 9. The inspection device failureconfirmation method according to claim 7, wherein the workpiece includesa fuel cell.